Protective Coordination of Overcurrent Relays for Distribution Feeder

• Main Authors: Lee, Chen-Wun, 李振文
• Other Authors: Huang, Pei-Hwa
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/16481829837399413337

碩士 === 國立臺灣海洋大學 === 電機工程學系 === 103 === Currently the protective relays for feeders from secondary substations of the utility include both types of electromagnetic relay and intelligent digital relay. It is common practice to use the per-unit method to calculate the currents of both three-phase and single-phase-to-ground faults, and the ANSI / IEEE or IEC over-current formula to plot the protective coordination curves. Then based on the coordination spacing and margin consider the feeder line, the branch line switch, the duty point, and the feeder breaker, the Protective Coordination Analysis Program is applied to plan the distribution system relay settings to determine the protective coordination curves as well as to find out a suitable protective coordination strategy among feeders, buses, and branch lines. The main purpose of this thesis is to apply both the Protective Coordination Analysis Program and the guidelines developed based on the experiences from field practices for obtaining reliable over-current protective relay settings in order to help engineers in improving the reliability of power supply. Once a failure occurs on the distribution system feeder, it can be promptly detected and effectively isolated to ensure the normal operation of the feeder. Moreover, several real cases are analyzed and the results are presented to demonstrate the feasibility of the proposed guidelines. It is shown that the results of this thesis will be helpful for the field practicing engineers.